Condensin and Chromosome Segregation in C. elegans

描述（由申请人提供）：在每次细胞分裂期间，基因组必须准确地复制和分离一套完整的染色体到每个子细胞中。染色体分离失败会对人类健康造成严重后果，因为产生染色体数目不适当的细胞会导致细胞死亡、出生缺陷或癌症。我们研究的长期目标是确定控制染色体分离的分子机制和机制，以确保基因组的稳定性。这一建议的重点是凝缩蛋白复合物，染色体组织和分离的保守关键调节因子。在减数分裂和有丝分裂染色体分离之前，凝缩蛋白结合并重新配置染色体，被认为是通过ATP水解将DNA缠绕成大环来实现的。我们试图了解多种凝缩蛋白复合物的功能和组成，这并不像最初想象的那样简单。利用模式生物秀丽隐杆线虫，我们发现凝缩蛋白不是一个简单的压实因子，而是在姐妹染色单体分解和着丝粒组织中发挥更复杂的作用。我们还证明了两种凝缩蛋白复合物的存在，它们具有重叠的成分，但在有丝分裂和X染色体基因调控中具有不同的功能。人类细胞也含有两种凝缩蛋白（凝缩蛋白I和凝缩蛋白II），它们都是有丝分裂所必需的，但具有不同的染色体定位、功能和调控。关于凝缩蛋白的重要未解问题包括确定每个复合物的精确功能，这些功能在多大程度上是独特的或冗余的，以及这些功能如何通过细胞周期和发育进行差异调节。在初步研究中，我们确定了额外的凝聚蛋白I和II亚基，为凝聚蛋白I在染色体分离中起作用提供了证据，并确定了可能将凝聚蛋白功能与细胞周期联系起来的激酶。我们建议：1)确定秀丽隐杆线虫复合体的组成和数量，并鉴定其相关蛋白。2)确定不同凝缩蛋白复合物在有丝分裂、减数分裂和基因调控中的不同功能。3)确定细胞周期激酶如何调节凝缩蛋白。这项研究将提供细胞如何确保在细胞分裂过程中遗传物质的准确分布，并避免在流产和实体瘤中经常观察到的染色体错误的见解。

DESCRIPTION (provided by applicant): During every cell division, the genome must accurately replicate and segregate a complete set of chromosomes into each daughter cell. Failures in chromosome segregation have severe consequences for human health, since creating cells with an inappropriate chromosome number can lead to cell death, birth defects, or cancer. The long-term goal of our research is to define the molecular machinery and mechanisms that govern chromosome segregation to ensure genomic stability. This proposal focuses on condensin protein complexes, conserved key regulators of chromosome organization and segregation. Condensins bind and reconfigure meiotic and mitotic chromosomes prior to their segregation, and are thought to do so by using ATP hydrolysis to wind DNA into large loops. We seek to understand the functions and composition of the multiple condensin complexes, which are not as straightforward as originally thought. Using the model organism C. elegans, we showed that condensin is not a simple compaction factor, but plays more complex roles in sister chromatid resolution and centromere organization. We also demonstrated the existence of two condensin complexes with overlapping components but distinct functions in mitosis and X chromosome gene regulation. It has since become clear that human cells also contain two condensins (condensin I and II) both necessary for mitosis but having distinct chromosome localization, function, and regulation. Important unanswered questions about condensins include determining the precise function each complex performs, to what extent these functions are unique or redundant, and how these functions are differentially regulated through the cell cycle and development. In preliminary studies we identified additional condensin I and II subunits, provided evidence for a condensin I that functions in chromosome segregation, and identified kinases that may tie condensin function to the cell cycle. We propose to: 1) Determine the composition and number of C. elegans complexes and identify their associated proteins. 2) Determine the distinct functions of different condensin complexes in mitosis, meiosis, and gene regulation. 3) Determine how condensin is regulated by cell cycle kinases. This research will provide insight into how cells ensure accurate distribution of the genetic material during cell division, and avoid the chromosomal errors often observed in miscarriages and solid tumors.